Validation of HPLC Multi-residue Method for Determination of Fluoroquinolones, Tetracycline, Sulphonamides and Chloramphenicol Residues in Bovine Milk

The occurrence of antibiotic residues in milk constitutes a potential risk to the health of consumers. The present study describes the optimisation and validation of a high-performance liquid chromatographic (HPLC) method for the simultaneous determination of sulphadiazine (SDZ), sulphamethoxazole (SMX), oxytetracycline (OTC), doxycycline (DOX), tetracycline (TC), enrofloxacin (ENRO) and chloramphenicol (CLP) residues in bovine milk using colchicine (COL) as internal standard. The determination of these antimicrobials was carried out on C-18 analytical column using high-performance liquid chromatographic-diode array detection (HPLC-DAD). The extraction method involving deproteinisation of the milk sample followed by a solid-phase extraction (SPE) clean-up of antibiotic residues has been developed. The method was validated according to the European Commission Decision 2002/657/EC and applied for the analysis of antibiotic residues in 21 raw milk samples collected from Ludhiana, Punjab, India. The recoveries for the studied antibiotics ranged from 83.3-111.8% with relative standard deviations between 3.5 and 16.2%. The limits of quantification for these antibiotics, with the exception of chloramphenicol, were below the maximum residue limits (MRLs), making the method suitable for performing routine analysis.